Answer:
Step-by-step explanation:
The rule for determining the cost-efficient combinations of inputs (K & L) to produce soft drinks is to compare the marginal product of each input (MPK and MPL) with their respective costs (r and w). The cost-efficient combination is achieved when the marginal product per dollar spent on each input is equal. In this case, the cost-efficient combination is achieved when the marginal product per dollar spent on machines (MPK / r) is equal to the marginal product per dollar spent on workers (MPL / w).